The present invention relates generally to a distributed data storage system, and in particular to techniques for managing data flow over a plurality of connections between primary and remote storage devices.
The information technology revolution brings with it an ever increasing need for more storage capacity for business enterprises. It is expected that the average Fortune 1000 company's storage requirement will more than double in the coming years. In addition, growth has brought shortages of skilled persons in the information technology field. These challenges confront many companies facing the need to expand and improve their information technology assets. Increasingly, companies are turning to storage based remote copy as a method of coping with the need to prevent data loss from disaster. Remote copy creates and manages mirror images of storage volumes between a local, or primary storage system, and a remote or secondary storage system. The primary and secondary storage systems may be located at a far distance from one another. The two disk storage systems are connected by a network, through which updates on a local disk system are copied to the remote disk system. Nowadays, there are many types of networks that can connect the two storage systems performing remote copying. For example, one type of network can be a fast, reliable, secure and relatively more expensive network, such as, for example, a T3 private network. Another type of network is relatively more slow, insecure, and cheap, such as the Internet, for example.
Business critical applications, like on line transaction processing (OLTP) for banking, finance, flight reservation systems, and so forth, requires remote copy capabilities with low response times, high security, and high reliability. Other types of applications, like WEB mirroring, data warehousing, data center consolidation, bulk data transfer, and the like, do not have such requirements, because these applications generally do not need to copy data in real time.
While certain advantages to present remote copy technologies are perceived, opportunities for further improvement exist. For example, according to conventional remote copy technology, the network carrier companies charge customers based upon a required throughput, and sometimes offer pay per services for private networks. For example, a network carrier company may charge customers according to network bandwidth used per month. However, some remote copy users would like to reduce the costs associated with data connections and will be willing to accept operational limitations to do so. For example, users can lower expenses by using different networks for remote copy depending on application characteristics. A user could employ the Internet for web mirroring applications, but use a T3 network for OLTP for banking, for example. Users who would like to use the storage for backup purposes do not need a full-time data connection. However, conventional technology does not provide the capability to manage access to the data transmission services of a network carrier based upon the charges for the access. Further, issues such as security are important concerns to both the user and the network carrier. For the user, this means that valuable information assets can be protected by restricting access to the data being sent to remote storage. For the network carrier, this means that data integrity is preserved for each of its customers, and that no user receives access that is not authorized by the network carrier.